The standard method of processing pig skin entails putting the carcass in a vessel so that the lower body surfaces--belly, legs, and hams--and the upper body portion--head, shoulders, and back--can be sprayed with hot water of 68.degree. C. to 70.degree. C. This loosens and softens the bristles, hard parts, and outer skin layer.
It is also known to use jets of steam to thus treat the skin while still on the carcass with heat and moisture. This method is fairly complex and usually results in uneven treatment of the skin as carcasses of different sizes are subject to the same treatment.
Subsequently the skin is singed, that is briefly exposed to a gas flame, to remove the remaining bristles and hair. It is then stripped from the carcass. The back skin is processed according to standard tanning techniques which normally damage another 10% of the material.
The main disadvantage of these systems is that a great deal of the skin is damaged either mechanically or thermally. Holes are poked and excessive heat breaks down the internal protein. In fact, a substantial portion of the skins recovered are so seriously damaged as to be unusable.